Method of making a non-woven fabric by splitting



April 8, 1969 F. K. MESEK ET AL 3,437,539

METHOD OF MAKING A NON-WOVEN FABRIC BY SPLITTINC- Filed Oct. 18, 1965ATTORNEY 3,437,539 METHOD OF MAKING A NON-WOVEN FABRIC BY SPLITTINGFrederick K. Mesek, Downers Grove, and William R. Strickel, Chicago,Ill., assignors to Johnson & Johnson, a corporation of New Jersey FiledOct. 18, 1965, Ser. No. 496,841 Int. Cl. 133% /26; 326d 3/28 US. Cl.156-254 4 Claims ABSTRACT OF THE DISCLOSURE Two non-woven fabrics aremade by splitting a composite web having an interlay of fibers having alarger diameter than the web fibers on each side of the interlay. Thecomposite web is split in the area of the interlay.

The present invention relates to non-woven fabrics and to a new andimproved method of making the same.

It has heretofore been proposed to make non-woven fabrics by firstforming a web of fibers, bonding the fibers on both sides of the webwith a bonding agent while taking care that the bonding agent does tnotcompletely penetrate the web, and then splitting the fiber web in theintermediate unbonded zone. One of the difficulties involved in makingsplit-fiber webs in this manner is the careful control of bondingrequired as any nonuniform penetration of the bonding agent into theintermediate portion of the web substantially affects the uniformity ofthe split product. A further problem is that the fibers on the surfaceof the split product, which were formerly a portion of the unimpregnatedcenter part of the web prior to splitting, are held only loosely byfiber to fiber friction. As a result there is substantial dusting orslufiing of fibers from this surface of the split webs.

It is, accordingly, an object of the present invention to preparenon-woven fibrous sheet materials by a split web method in whichsplitting is not dependent solely on controlled penetration of thebonding agent used. It is a further object of the present invention toprepare nonwoven fibrous sheet materials in which the amount of loosesurface fibers on the split web is substantially reduced. Other objectsand advantages of this invention will become apparent from the followingdescription taken in connection with the accompanying drawings, whereinare set forth by way of illustration and example certain embodiments ofthis invention.

According to the present invention in preparing the fiber web which isto be split, a layer of relatively large denier fibers is interposed inthe web in the plane along which splitting is to take place. It has beendiscovered that where a layer of fibers having a denier substantiallylarger than the fibers from which the remainder of the web is formed isinterposed in the web and the entire web then through bonded, that onsplitting, the web will split in the zone of the larger diameter fibers.This is true whether or not the web is completely impregnated with thebonding agent.

By bonding all fibers with the bonding agent prior to the splittingoperation the occurrence of loose fibers on the split surface of theseparate sheets so formed is substantially eliminated. Also, by placingthe interlay of larger denier fibers in the web along the line wheresplitting is desired, excellent control of the splitting operation withthe formation of highly uniform products can be obtained. Webs can beprepared which are adapted to be split into more than two separatesheets by interposlng into the web, during its formation, more than onelayer of larger denier fibers. The layers of larger denier fibers areseparated by layers of the smaller denier fibers and the layered sheetso formed then through bonded prior to splitting.

The fibers in the zone or layer along which splitting is to occur shouldhave a denier of at least twice that of the adjacent fibers betweenwhich it is sandwiched. The denier of the interlay of larger denierfibers may be as much as ten times that of the denier of the fibers oneach side of the interlay or even larger, and controlled splitting ofthe web will still be obtained. However, as the difference in sizebecomes greater particularly where it exceeds about six times that ofthe fibers of the adjacent layers, it becomes necessary to use largeramounts of the finer denier fibers in order to obtain a uniform andattractive appearing fiber layer over the interlay of large denierfibers because of the relatively uneven surface upon which the finerdenier fibers are laid. Accordingly, in practicing the presentinvention, it is generally preferred to have the denier of the fibersforming the fiber interlay along which splitting is to occur about twoto six times that of the adjacent fibers and generally not exceedingmore than about ten times the denier of the adjacent fiber layers.

The present invention is further illustrated by reference to thedrawings in which FIGURE 1 is an edge view of a web prior to splitting;

FIGURE 2 is a perspective view of the web of FIG- URE 1 in which thesheet of material is partially separated by splitting into two sheets;

FIGURE 3 is a perspective view of one of the sheets of FIGURE 2 aftersplitting;

FIGURE 4 is a schematic view illustrating one method of splitting theweb of FIGURE 1;

FIGURE 5 is an edge view of a fiber Web prior to splitting which web isdesigned to be split into more than two sheets;

FIGURE 6 is a perspective view of the fiber web of FIGURE 5 showing thesame partially split along each of the interposed large denier fiberlayers;

FIGURE 7 is a sheet from one of the outer surfaces of the web of FIGURE5 after being separated by splitting; and

FIGURE 8 is a sheet from one of the inner portions of the web of FIGURE5 after being separated by splitting.

In practicing the present invention a web, such for example asillustrated in FIGURE 1, is first built up by laying down fibers in aseries of superimposed fiber layers. The fiber layers, which may bedeposited by any conventional fiber-laying apparatus, may be formed ofcarded fibers or may be formed of randomly disposed fibers depending onthe nature of the particular product desired. As better control of thethickness and uniformity of the fiber layer deposited is obtained withcarded fibers, it is generally preferred to form the fiber layers,particularly the center fiber layer of carded fibers rather thanrandomly disposed fibers.

Although fibers of various types may be used in practicing the presentinvention, in describing the invention wizh reference to the drawings anall rayon fiber product is described.

The laminate web 1 illustrated in FIGURE 1 is formed by first layingdown a layer 2 of carded fibers 3 of 1.5 denier rayon having a length ofabout 1%,". These fibers are laid to a fiber weight of about 160 grains.Superimposed on this fiber layer is a layer 4 of carded rayon fibers 5having a denier of 5.5 and a length of about 1% the fibers being laid toa weight of about grains. A layer 6 of fibers 7 of 1.5 denier and lengthof about 1 is then deposited on the fiber layer 4 of larger denierfibers 5 to a weight of about grains. The fiber web 1 so formed is thenimpregnated with a solution of acrylate binder, such for example asHycar resin hinder, the impregnation being done by any conventionalmethod as passing the same between rolls which are wetted with thebinder solution. The impregnated web is dried and heated for 3 minutesat about 310 F. to set the binder. The amount of binder used will dependon the properties desired in the final product and will generally be ona solids basis of about 1% to 50% by weight of the fiber web.

The resulting bonded fiber web 1 is separated into two separate sheets 8and 9, as illustrated in FIGURE 2, by splitting along the interlay 4 oflarge denier fibers 5. Sheet 8 has one surface composed of the largedenier fibers 5 and the other surface composed of the finer denierfibers 7 whereas sheet 9 has one surface of large denier fibers 5 andthe other surface of the finer fibers 3. Sheet 9 is best illustrated inFIGURE 3 which gives a perspective view of the same.

The interposed layer 4 of large denier fibers 5 is preferably relativelythin to provide primarily a control for the splitting of the fiber web.The larger denier fibers 5 making up the interposed layer 4 in theillustration given would generally be deposited in a weight range ofabout 20 grains to 200 grains per square yard.

The splitting of the web can be readily accomplished by passing betweentwo rolls the web being split by drawing sheet 8 around one of the rollsand sheet 9 around the other roll as the web passes from the nip betweenthe rolls. This is illustrated schematically in FIGURE 4 where fiber Web1 is passed between rolls 10 and 11 with splitting occurring after theweb passes from between the two rolls. Splitting being aided by a wedgeshaped member 12 positioned near the exit side of the nip between rolls10 and 11. After initiating the split, sheets 8 and 9,. resulting fromsplitting web 1, are drawn respectively around rolls 10 and 11.

As previously indicated, more than two sheets can be made simultaneouslyby practicing the process of the present invention. This is bestillustrated by reference to FIG- URES 5 through 8 of the drawings.

In FIGURE 5 is illustrated a cross-sectional view of a web formed ofsuperimposed fiber layers and impregnated with a bonding agent in amanner similar to that described in the preparation of the web ofFIGURE 1. The web 13 of FIGURE 5, however, has four fiber layers 14, 15,16 and 17 formed of relatively small denier fibers 25 with layers 18, 19and 20 of larger denier fibers 26 placed in between. Web 13, afterthrough bonding, is split into four separate sheets 21, 22, 23 and 24 asbest illustrated in FIGURE 6. Splitting in each instance occurs along aninterposed layer of large denier fibers. Referring to FIG- URE 6, theresulting separate sheets 21, 22, 23 and 24 obtained by splitting web 13are each formed of both the small denier fibers and the larger denierfibers 26. Sheets 21 and 24 formed from the outer portions of web 13differ from sheets 22 and 23 obtained from the inner portion of web 13in that sheets 21 and 24 each have one surface formed of the relativelysmall denier fibers 25 and the other surface formed of the larger denierfibers 26. Sheets 22 and 23, however, have a three ply construction inwhich a layer of the relatively small denier fibers 25 is sandwiched inbetween two outer layers of the larger denier fibers 26. Sheets 24 and23 are illustrated respectively in FIGURES 7 and 8 of the drawings.

As previously indicated, the practice of the present invention is notlimited to the use of any particular type of fiber but various types offibers may be used. Thus, any of the natural fibers such as cotton,linen, hemp, silk, wool or wood pulp fibers or synthetic fibers such asrayon, acetate, polyester, acrylic or modacrylic fibers may be used.Where different fibers are used for the interposed layer of relativelylarge denier fiber than for the finer denier fibers, a bonding agentshould be used which is not selective for the fibers of the interposedweb of the larger denier fibers.

The following examples will help further to illustrate the practice ofthe present invention. The examples are given for the purposes ofillustration only, however, and the invention is not limited thereto.

Example I A carded web is prepared having alternate cotton, rayon,cotton layers as follows:

Cotton 300 grains per square yard, 5.5 denier rayon grains per squareyard, Cotton 600 grains per square yard.

The cotton has a Micronaire fineness of approximately 4.0 which would beequivalent to 1.4 denier. The web is impregnated with a 1 percent solidssolution of cornstarch to give a binder pickup on a solids bases ofabout 2.5 percent.

The impregnated web is dried and then split into two separate sheets bypassing through rolls and splitting in a manner similar to thatillustrated in FIGURE 4 of the drawings. The sheets so formed each haveone fuzzy surface of the 5.5 denier rayon and one relatively smoothsurface of the cotton. Splitting occurs uniformly in the rayon layer.

Example 11 A web is prepared having the following construction:

1.5 denier rayon 300 grains per square yard, 5.5 denier rayon 70 grainsper square yard, 1.5 denier rayon 300 grains per square yard.

The web is impregnated with Hycar No. 2671 (an acrylate resin binder) toa pickup weight of 70 grains of binder per square yard of web on asolids basis. The impregnated web is dried and cured at 310 F. for 3minutes. The web is then split in the manner previously described.Splitting occurs readily and uniformly in the center layer of 5.5 denierrayon.

Example III A three layer Web is formed using as the outer layers a 5050blend of 1.5 denier rayon and nonabsorbent comber cotton and an innerlayer of 5.5 denier rayon. The fiber length of the rayon for both layersis approximately 194 The fibers are bonded by impregnating with asolution of Hycar 2671 and drying and curing as in the previous example.The completed web splits uniformly through the center layer of 5.5denier rayon.

Example IV Using 1.5 denier rayon of 1%3" fiber length as the outerlayers, three layer webs are prepared containing respectively a centerfiber interlay of 3.0 denier rayon, a center fiber interlay of 6.0denier dynel, and a 50 50 blend of 5.5 denier rayon and nonabsorbentcomber cotton. The webs with the respective interlays are bonded withHycar Resin 2600X84 and then split in the manner described for theprevious examples. The webs in each instance split readily along thecenter layer of interposed larger denier fibers.

Particular embodiments of the invention have been used to illustrate thesame. The invention, however, is not limited to these specificembodiments. In view of the foregoing disclosure variations ormodifications thereof will be apparent, and it is intended to includewithin the invention all such variations and modifications except as donot come within the scope of the appended claims.

Having thus described our invention, we claim:

1. The method of making non-woven fabric comprising the steps of:forming a composite web having at least one interlay of fibers having adiameter at least twice the diameter of the fibers in said web on eachside of said fiber interlay; bonding the larger diameter fibers in saidinterlay and said adjacent smaller diameter fibers with a bonding agent;and then splitting said web in the area of said fiber interlay.

2. The method of claim 1 wherein the interlay is formed of fibers havinga diameter not in excess of 10 times the diameter of the adjacentfibers.

6 3. The method of claim 1 wherein the interlay is formed ReferencesCited of fibers havlng a diameter from 2 to 6 times the diameter FOREIGNPATENTS of the ad acent fibers.

4. The method of claim 3 wherein said composite web 972,633 8/1963 Greatis formed with a plurality of fiber interlays and said web is split atsaid plurality of interlays to form a plurality of 5 DOUGLAS DRUMMONDPrimary Examiner individual webs.

